https://github.com/ibaryshnikov/future-hs

Future Monad
https://github.com/ibaryshnikov/future-hs

haskell rust tokio

Last synced: 6 days ago
JSON representation

Future Monad

• Host: GitHub
• URL: https://github.com/ibaryshnikov/future-hs
• Owner: ibaryshnikov
• License: mit
• Created: 2024-04-17T12:59:52.000Z (9 months ago)
• Default Branch: master
• Last Pushed: 2024-05-31T07:26:47.000Z (7 months ago)
• Last Synced: 2024-11-09T06:44:04.326Z (2 months ago)
• Topics: haskell, rust, tokio
• Language: Haskell
• Homepage:
• Size: 19.5 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# future-hs

`Future` Monad for Rust futures in Haskell.

This is a research project which started as part

of [iced-hs](https://github.com/ibaryshnikov/iced-hs)

Built with [tokio](https://github.com/tokio-rs/tokio)

## Semantics

```

pure a

is

async move { a }

callA >> callB

is

call_a.await;

call_b.await;

callA >>= callB

is

let a = call_a.await;

call_b(a).await; 

```

## Example

```haskell

import Future

import Future.Time

callA :: Future Int

callA = do

  delaySecs 2

  pure 1

callB :: Int -> Future Int

callB a = do

  delaySecs 2

  pure $ a + 4

example :: Future ()

example = do

  a <- callA

  b <- callB a

  liftIO $ putStrLn $ show b -- prints 5

main :: IO ()

main = run example

```

There are `race` and `concurrent` functions:

```haskell

race :: Future a -> Future b -> Future (Either a b)

concurrent :: Future a -> Future b -> Future (a, b)

```

For example:

```haskell

do

  let ma = callA

  let mb = callB

  (a, b) <- concurrent ma mb

```

`race` is a wrapper around

[tokio::select!](https://docs.rs/tokio/1.37.0/tokio/macro.select.html)

and `concurrent` uses

[tokio::join!](https://docs.rs/tokio/1.37.0/tokio/macro.join.html)

## Usage

```bash

# build libfuture_hs.a

./build_rust.sh

# call ghc

# note that -threaded is required

ghc -threaded -ipath/to/this/repo path/to/libfuture_hs.a main.hs

```